1. Field of the Invention
The invention relates to a multioperation accelerator of simple design, usable more particularly in radiotherapy for treatments using low or average amounts of energy.
2. Description of the Prior art
In radiotherapy a distinction is made, among others, of two types of equipment, the radiation generators using radioactive sources, such for example as cobalt, and the particle (particularly electron) accelerators. These latter offer a great flexibility of use and allow high energies to be reached up to 40 MeV electrons and 25 MeV photons. However, such apparatus are costly. Particularly, the systems for adjusting and varying the power of the beam (so as to obtain the different operating conditions) acting on the acceleration parameters, particularly the HF power, have a great influence on the cost price of the installation.
Furthermore, the cobalt generator has its own particular qualities which means that it is very greatly appreciated by doctors although handling of the radioactive sources requires precautions. The radiation of the cobalt is a photon radiation which is very penetrating despite a low energy (1.3 MeV photons) since 50% of the maximum dose is still available at a depth of 12 cm in the tissue. On the other hand, the "skin dose" is relatively high which means, in certain cases, surface irradiation which is too high with consequent risks of burning.
Now, at the present time, it is possible to construct accelerator structures capable of supplying the electron energy (about 4 MeV) required for obtaining 1.3 MeV photons as with cobalt, and this for a relatively low cost price.